Net bisimilarity is a truly concurrent behavioral equivalence. Consider the three nets in Figure REF , which are the semantics
of the CCS-like [1]}, [2]} terms \(a.b.\mbox{\bf 0}+ b.a.\mbox{\bf 0}\) , \(a.\mbox{\bf 0}\mbox{$\,|\,$}b.\mbox{\bf 0}\)  and \(a.C \mbox{$\,|\,$}b.\mbox{\bf 0}\) 
(with \(C  \doteq \mbox{\bf 0}\) ), respectively, according to the net semantics in [3]}.
Of course, \(s_1\)  is not net bisimilar to \(s_4 \oplus s_5\)  because these two markings have different size; as a matter of fact,
these two markings generate
different partial orders of actions. Moreover,
\(s_4 \oplus s_5\)  is not net bisimilar to \(s_6 \oplus s_7\)  because \(s_4 \nsim _n s_6\) : after the execution of \(a\) , the reached markings
(namely, \(\theta \)  and \(s_8\) ) are not net bisimilar. So, net bisimilarity not only observes the partial order of the actions performed, but also the
size of the distributed state. In fact, in the next section we will prove that \(\sim _n\)  coincides with causal-net bisimilarity \(\sim _{cn}\) .
